Functional material, dispersion containing the functional material, and process for producing the functional material

ABSTRACT

A functional material comprising fine coloring particles having an average primary particle diameter of 1 to 50 nm in a dried state, and having a BET specific surface area value of to 500 m 2 /g and a light transmittance of not less than 80%. The functional material composed of fine coloring particles, exhibits not only an excellent transparency but also a high tinting strength and a clear hue.

BACKGROUND OF THE INVENTION

The present invention relates to a functional material, a dispersioncontaining the functional material, and a process for producing thefunctional material. More particularly, the present invention relates toa functional material composed of fine coloring particles, whichexhibits not only an excellent transparency but also a high tintingstrength and a clear hue, a dispersion containing the functionalmaterial, and a process for producing the functional material.

As well known in the art, organic pigments have been used as colorantsfor paints, resins, printing inks or the like according to applicationsthereof. Therefore, the organic pigments have been generally required tohave a high tinting and a good transparency.

The organic pigments are produced by first forming fine primaryparticles having a particle size as small as about 20 to 100 nm from thepigments in a molecular state produced by a chemical reaction, and thensubjecting the thus obtained primary particles to filtering, washing anddrying steps. However, the fine primary particles tend to beagglomerated because of a very high surface energy thereof, therebyforming aggregates (secondary particles). It is well known that theformation of the secondary particles remarkably proceeds, in particular,upon the drying step.

The organic pigments in the form of fine coloring particles have apossibility of exhibiting novel functions. Therefore, it has beenexpected that the organic pigments are used in other applications thanpigments, for example, as nonlinear optical materials.

As the method for producing such fine coloring particles, there areknown, for example, a method of applying an ultrasonic wave to a liquiddispersion containing fine functional particles dispersed therein toinhibit agglomeration thereof (Japanese Patent Application Laid-open No.11-269432 (1999)); and a method of producing fine coloring particles ofan organic compound by irradiating a laser beam to the organic compound(Japanese Patent Application Laid-open No. 2001-113159).

However, in any of these conventional methods, it may be difficult toobtain fine coloring particles having a primary particle diameter of notmore than 50 nm. At present, it has been strongly required to providefine coloring particles having a high tinting strength as well as anexcellent transparency and a clear hue. However, the conventionalmethods have failed to obtain such fine coloring particle satisfying theabove properties.

As a result of the present inventors' earnest studies, it has been foundthat by mixing inorganic compound particles with a gluing agent understirring to form a gluing agent coat on the surface of the inorganiccompound particles, mixing organic pigments with the obtained inorganiccompound particles coated with the gluing agent under stirring to adherethe organic pigments onto the surface of the gluing agent coat, therebyobtaining composite particles, and then dissolving either the inorganiccompound particles as core particles only or both of the inorganiccompound particles and the gluing agent from the composite particles,the obtained functional material composed of fine coloring particleshave a fine primary particle diameter, and can exhibit a high tintingstrength as well as an excellent transparency and a clear hue. Thepresent invention has been attained on the basis of this finding.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a functional materialcomposed of fine coloring particles having a fine primary particlediameter, which exhibits a high tinting strength as well as an excellenttransparency and a clear hue.

Another object of the present invention is to provide a dispersionexhibiting an excellent transparency and a clear hue.

To accomplish the aims, in a first aspect of the present invention,there is provided a functional material comprising fine coloringparticles having an average primary particle diameter of 1 to 50 nm in adried state, and having a BET specific surface area value of 30 to 500m²/g and a light transmittance of not less than 80% when evaluated bythe following method:

(1) blending 5 g of the functional material and the following componentsas a paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer.

In a second aspect of the present invention, there is provided afunctional material comprising fine coloring particles having an averageprimary particle diameter of 1 to 50 nm in a dried state, and having aBET specific surface area value of 30 to 500 m²/g and a lighttransmittance of not less than 80% when evaluated by the followingmethod:

(1) blending 5 g of the functional material and the following componentsas a paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700=m using a self-recording photoelectricspectrophotometer,

which is produced by a process comprising: mixing inorganic compoundparticles with a gluing agent under stirring to form a gluing agent coaton surface of the inorganic compound particles;

adding organic pigments to the inorganic compound particles coated withthe gluing agent, and mixing the resultant mixture under stirring toadhere the organic pigments on the gluing agent coat, thereby obtainingcomposite particles; and

dissolving the inorganic compound particles only or both of theinorganic compound particles and the gluing agent from the compositeparticles.

In a third aspect of the present invention, there is provided adispersion comprising:

a functional material comprising fine coloring particles having anaverage primary particle diameter of 1 to 50 nm in a dried state, andhaving a BET specific surface area value of 30 to 500 m²/g and a lighttransmittance of not less than 80% when evaluated by the followingmethod:

(1) blending 5 g of the functional material and the following componentsas a paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer; and

a dispersion base material comprising water, a mixture of water and awater-soluble organic solvent, or an organic solvent,

said functional material being contained in an amount of 5 to 1,000parts by weight based on 100 parts by weight of the dispersion basematerial.

In a fourth aspect of the present invention, there is provided a resincomposition comprising:

a functional material comprising fine coloring particles having anaverage primary particle diameter of 1 to 50 nm in a dried state, andhaving a BET specific surface area value of 30 to 500 m²/g and a lighttransmittance of not less than 80% when evaluated by the followingmethod:

(1) blending 5 g of the functional material and the following componentsas a paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer; and

a thermoplastic resin,

said functional material being contained in an amount of 0.01 to 200parts by weight based on 100 parts by weight of the thermoplastic resin.

In a fifth aspect of the present invention, there is provided an ink-jetprinting ink comprising:

a functional material comprising fine coloring particles having anaverage primary particle diameter of 1 to 50 nm in a dried state, andhaving a BET specific surface area value of 30 to 500 m²/g and a lighttransmittance of not less than 80% when evaluated by the followingmethod:

(1) blending 5 g of the functional material and the following componentsas a paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer; and

an ink base solution comprising a dispersant and water,

said functional material being contained in an amount of 1 to 20% byweight based on the weight of the ink base solution.

In a sixth aspect of the present invention, there is provided a processfor producing a functional material comprising fine coloring particles,comprising:

mixing inorganic compound particles with a gluing agent under stirringto form a gluing agent coat on surface of the inorganic compoundparticles;

adding organic pigments to the inorganic compound particles coated withthe gluing agent, and mixing the resultant mixture under stirring toadhere the organic pigments on the gluing agent coat, thereby obtainingcomposite particles; and

dissolving the inorganic compound particles only or both of theinorganic compound particles and the gluing agent from the compositeparticles.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail below.

First, the functional material composed of fine coloring particlesaccording to the present invention is described.

The functional material of the present invention composed of finecoloring particles, has an average particle diameter of usually 1 to 150μm preferably 1 to 100 nm, more preferably 1 to 50 nm. When the averageparticle diameter of the functional material is more than 150 nm, thetinting strength and transparency thereof tend to be deteriorated due tolarge particle size. The functional material according to the presentinvention is constituted by a flocculate of the fine coloring particlesin a dried state, and the average particle diameter is of the flocculatethereof.

Also, the fine coloring particles in a dried state according to thepresent invention have an average primary particle diameter of usually 1to 50 nm, preferably 1 to 40 nm, more preferably 1 to 30 nm. The finecoloring particles according to the present invention which are aflocculate in a dried state, easily become separated fine particles by aweak force and the average primary particle diameter is of theseparated-particles as primary particles.

The functional material composed of the fine coloring particlesaccording to the present invention may have any suitable shape such asindeterminate shape, spherical shape, granular shape, polyhedral shape,acicular shape, spindle shape, rice-ball shape, flake shape, scale shapeand plate shape, and may also have a hollow structure thereof.

The functional material composed of the fine coloring particlesaccording to the present invention has a BET specific surface area valueof usually 30 to 500 m²/g, preferably 40 to 450 m²/g, more preferably 45to 400 m²/g. When the BET specific area value is less than 30 m²/g, theobtained functional material may become coarse, resulting indeteriorated tinting strength and poor transparency.

The functional material composed of the fine coloring particlesaccording to the present invention has a tinting strength of usually notless than 110%, preferably not less than 115%, more preferably not lessthan 120%. When the tinting strength is less than 110%, such a tintingstrength of the functional material is merely similar to that of theconventional organic pigments, so that the functional material fails toshow a sufficiently high tinting strength.

The functional material composed of the fine coloring particlesaccording to the present invention has a light transmittance of usuallynot less than 80%, preferably not less than 85%, more preferably notless than 90% when evaluated by the following method:

(1) blending 5 g of the functional material (fine coloring particles)(which correspond to 9.9 parts by weight based on 100 parts by weight oftotal amount of the functional material and a paint base material) andthe following components as a paint base material at the below-mentionedmixing ratio in a 250 ml glass bottle, and mixing and dispersing theresultant mixture together with 160 g of 3 mmφ glass beads using a paintshaker for 120 minutes, thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(3) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer, in which the light transmittance (%) is expressed bythe highest peak value.

When the light transmittance is less than 80%, the transparency maybecome insufficient.

Next, the dispersion according to the present invention is described.

The dispersion according to the present invention is in the form of awater-based dispersion comprising the functional material composed ofthe fine coloring particles and water and/or a water-soluble organicsolvent as a dispersion base material, or in the form of a solvent-baseddispersion comprising the functional material composed of the finecoloring particles and an organic solvent as a dispersion base material.The dispersion of the present invention contains the functional materialin an amount of usually 5 to 1000 parts by weight, preferably 10 to 800parts by weight based on 100 parts by weight of the dispersion basematerial.

The dispersion base material includes a solvent component composed ofeither water and/or a water-soluble organic solvent, or an organicsolvent, as well as optional components such as resins, defoamingagents, extender, drying promoters, surfactants, hardening accelerators,various assistants, etc.

Examples of the solvent used for the water-based dispersion may includewater; water-soluble organic solvents ordinarily used for water-basedpaints, e.g., alcohol-based solvents such as ethyl alcohol, propylalcohol and butyl alcohol, glycol ether-based solvents such as propyleneglycol monomethyl ether, propylene glycol monoethyl ether, ethyleneglycol monopropyl ether, methyl cellosolve, ethyl cellosolve, propylcellosolve and butyl cellosolve, oxyethylene or oxypropylene additionpolymers such as diethylene glycol, triethylene glycol, polyethyleneglycol, dipropylene glycol, tripropylene glycol and polypropyleneglycol, alkylene glycols such as ethylene glycol, propylene glycol and1,2,6-hexane triol, glycerin, 2-pyrrolidone, or the like; or a mixedsolvent of water and the above water-soluble organic solvent.

Examples of the solvent used for the solvent-based dispersion mayinclude solvents ordinarily used for solvent-based paints, e.g., soybeanoil, toluene, xylene, thinner, butyl acetate, methyl acetate, methylisobutyl ketone, glycol ether-based solvents such as propylene glycolmonomethyl ether, propylene glycol monoethyl ether, ethylene glycolmonopropyl ether, methyl cellosolve, ethyl cellosolve, propylcellosolve, butyl cellosolve and propylene glycol monomethyl ether,ester-based solvents such as ethyl acetate, butyl acetate and amylacetate, aliphatic hydrocarbon-based solvents such as hexane, heptaneand octane, alicyclic hydrocarbon-based solvents such as cyclohexane,petroleum-based solvents such as mineral spirits, ketone-based solventssuch as acetone and methyl ethyl ketone, alcohol-based solvents such asmethyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol,aliphatic hydrocarbons or the like.

Examples of the resins used for the water-based dispersion may includeresins ordinarily used for water-based paints or aqueous inks such aswater-soluble acrylic resins, water-soluble styrene-maleic acidcopolymer resins, water-soluble alkyd resins, water-soluble melamineresins, water-soluble urethane emulsion resins, water-soluble epoxyresins, water-soluble polyester resins or the like.

Examples of the resins used for the solvent-based dispersion may includeresins ordinarily used for solvent-based paints or oil-based printinginks such as acrylic resins, alkyd resins, polyester resins,polyurethane resins, epoxy resins, phenol resins, melamine resins, aminoresins, vinyl chloride resins, silicone resins, rosin-based resins suchas gum rosin and lime rosin, maleic acid resins, polyamide resins,nitrocellulose, ethylene-vinyl acetate copolymer resins, rosin-modifiedresins such as rosin-modified phenol resins and rosin-modified maleicacid resins, petroleum resins or the like.

The dispersion of the present invention has a light transmittance ofusually not less than 60%, preferably not less than 65%, more preferablynot less than 70%.

In the case of the water-based dispersion, the light transmittancethereof is measured as follows. Namely, the fine coloring particles asthe functional material are added to water to prepare a water dispersionhaving a concentration of 0.04% by weight. The thus prepared waterdispersion is placed in a quartz cell, and the light transmittancethereof is measured in a wavelength region of 380 to 700 nm using aself-recording photoelectric spectrophotometer, in which the lighttransmittance (%) is expressed by the highest measured value.

In the case of the solvent-based dispersion, the light transmittancethereof is measured as follows. Namely, the fine coloring particles asthe functional material are added to toluene to prepare a toluenedispersion having a concentration of 0.04% by weight. The thus preparedtoluene dispersion is placed in a quartz cell, and the lighttransmittance thereof is measured in a wavelength region of 380 to 700nm using a self-recording photoelectric spectrophotometer, in which thelight transmittance (%) is expressed by the highest measured value.

Next, the process for producing the fine coloring particles as thefunctional material according to the present invention is described.

Examples of the inorganic compound particles as core particles used inthe present invention may include metals, alloys, oxides, hydroxides,carbonates, nitrides or the like which are soluble in acids or alkalis.Specific examples of the inorganic compound particles may include metalssuch as metal iron; oxides such as silica, magnetite, hematite,maghemite, zinc oxide and magnesium oxide; hydroxides such as goethite,magnesium hydroxide and hydrotalcite; carbonates such as calciumcarbonate, strontium carbonate and barium carbonate; nitrides such astrisilicon tetranitride (Si₃N₄); or the like. Among these inorganiccompound particles, preferred are oxides, hydroxides and carbonates, andmore preferred are silica, magnetite, zinc oxide and calcium carbonate.

The particle shape of the inorganic compound particles as core particlesused in the present invention is not restricted to particular one, andthe inorganic compound particles may be granular particle such asspherical particles, granular particles, octahedral particles,hexahedral particles and polyhedral particles; acicular particle such asacicular particles, spindle-shaped particles and rice ball-shapedparticles; plate-shaped particles such as plate-shaped particles,flake-shaped particles and scale-shaped particles; or the like.

The inorganic compound particles used in the present invention have anaverage particle diameter of usually 0.001 to 1.0 μm, preferably 0.005to 0.75 μm, more preferably 0.01 to 0.75 μm.

The inorganic compound particles used in the present invention have aBET specific surface area value of usually 1 to 250 m²/g, preferably 2to 200 m²/g.

The gluing agent used in the present invention is not particularlyrestricted as long as the organic pigments can be adhered onto thesurface of the inorganic compound particles through the gluing agent.Examples of the preferred gluing agents may include organosiliconcompounds such as alkoxysilanes, fluoroalkylsilanes and polysiloxanes;various coupling agents such as silane-based coupling agents,titanate-based coupling agents, aluminate-based coupling agents andzirconate-based coupling agents; oligomers or polymer compounds; or thelike. These gluing agents may be used alone or in the form of a mixtureof any two or more thereof. In the consideration of adhesion strength ofthe organic pigments onto the surface of the inorganic compoundparticles through the gluing agent, the more preferred gluing agents arethe organosilicon compounds such as alkoxysilanes, fluoroalkylsilanesand polysiloxanes, and various coupling agents such as silane-basedcoupling agents, titanate-based coupling agents, aluminate-basedcoupling agents and zirconate-based coupling agents.

In particular, in the case where fine silica particles are used as theinorganic compound particles, it is preferable to use the organosiliconcompounds or the silane-based coupling agents as the gluing agent.

As organosilicon compounds used in the present invention, at least oneorganosilicon compound selected from the group consisting of (1)organosilane compounds obtained from alkoxysilane compounds; (2)polysiloxanes, (3) modified polysiloxanes, (4) terminal-modifiedpolysiloxanes and (5) fluoroalkyl organosilane compounds obtained fromfluoroalkylsilane compounds.

The organosilane compounds can be produced from alkoxysilane compoundsrepresented by the formula (I):

R¹ _(a)SiX_(4-a)  (I)

wherein R¹ is C₆H₅—, (CH₃)₂CHCH₂— or n-C_(b)H_(2b+1)— (wherein b is aninteger of 1 to 18); X is CH₃O— or C₂H₅O—; and a is an integer of 0 to3.

Specific examples of the alkoxysilane compounds may includemethyltriethoxysilane, dimethyldiethoxysilane, phenyltriethyoxysilane,diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane,phenyltrimethoxysilane, diphenyldimethoxysilane,isobutyltrimethoxysilane, decyltrimethoxysilane or the like.

Among these alkoxysilane compounds, in view of the adhering effect ofthe organic pigments to the surface of the inorganic compound particles,methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane,isobutyltrimethoxysilane and phenyltriethyoxysilane are preferred, andmethyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilaneand phenyltriethyoxysilane are more preferred.

As the polysiloxanes, there may be used those compounds represented bythe formula (II):

wherein R² is H— or CH₃—, d is an integer of 15 to 370, and d′ is aninteger of 15 to 370.

As the modified polysiloxanes, (a) there may be used polysiloxanesmodified with polyethers represented by the formula (III):

wherein R³ is —(—CH₂—)_(h)—; R⁴ is —(—CH₂—)_(i)—CH₃; R⁵ is —OH, —COOH,—CH═CH₂, —C(CH₃)═CH₂ or —(—CH₂—)_(j)—CH₃; R⁶ is —(—CH₂—)_(k)—CH₃; g andh are an integer of 1 to 15; i, j and k are an integer of 0 to 15; e isan integer of 1 to 50; and f is an integer of 1 to 300;

(b) polysiloxanes modified with polyesters represented by the formula(IV):

wherein R⁷, R⁸ and R⁹ are —(—CH₂—)_(q)— and may be the same ordifferent; R¹⁰ is —OH, —COOH, —CH═CH₂, —CH(CH₃)═CH₂ or —(—CH₂—)_(r)—CH₃;R¹¹ is —(—CH₂—)_(s)—CH₃; n and q are an integer of 1 to 15; r and s arean integer of 0 to 15; e′ is an integer of 1 to 50; and f′ is an integerof 1 to 300; and

(c) polysiloxanes modified with epoxy compounds represented by theformula (V):

wherein R¹² is —(—CH₂—)_(v)—; v is an integer of 1 to 15; t is aninteger of 1 to 50; and u is an integer of 1 to 300; or a mixturethereof.

As the terminal-modified polysiloxanes, there may be used thoserepresented by the formula (IV):

wherein R¹³ and R¹⁴ are —OH, R¹⁶OH or R¹⁷COOH and may be the same ordifferent; R¹⁵ is —CH₃ or —C₆H₅; R¹⁶ and R¹⁷ are —(—CH₂—)_(y)—; y is aninteger of 1 to 15; w is an integer of 1 to 200; and x is an integer of0 to 100.

Among these polysiloxanes, in view of the adhering effect of the organicpigment, polysiloxanes having methyl hydrogen siloxane units, thepolysiloxanes modified with the polyethers represented by the formula(III), and the polysiloxanes whose terminals are modified withcarboxylic acid groups, are preferred.

The fluoroalkyl organosilane compounds may be produced fromfluoroalkylsilane compounds represented by the formula (VII):

CF₃(CF₂)_(z)CH₂CH₂(R¹⁸)_(a′)SiX_(3-a′)  (VII)

wherein R¹⁸ is CH₃—, C₂H₅—, CH₃O— or C₂H₅O—; X is CH₃O— or C₂H₅O—; and zis an integer of 0 to 15; and a′ is an integer of 0 to 2.

Specific examples of the fluoroalkylsilane compounds may includetrifluoropropyl trimethoxysilane, tridecafluorooctyl trimethoxysilane,heptadecafluorodecyl trimethoxysilane, heptadecafluorodecylmethyldimethoxysilane, trifluoropropyl triethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyl triethoxysilane, or the like.

Among these fluoroalkylsilane compounds, in view of the adhering effectof the organic pigment, trifluoropropyl trimethoxysilane,tridecafluorooctyl trimethoxysilane and heptadecafluorodecyltrimethoxysilane are preferred, and trifluoropropyl trimethoxysilane andtridecafluorooctyl trimethoxysilane are more preferred.

As the silane-based coupling agents, there may be exemplifiedvinyltrimethoxysilane, vinyltriethoxysilane,γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane,γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane,N-β(aminoethyl)-γ-aminopropyltrimethoxysilane,γ-glycidoxypropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilaneor the like.

As the titanate-based coupling agents, there may be exemplifiedisopropyltristearoyl titanate,isopropyltris(dioctylpyrophosphate)titanate,isopropyltri(N-aminoethyl-aminoethyl)titanate,tetraoctylbis(ditridecylphosphate)titanate,tetra(2,2-diaryloxymethyl-1-butyl)bis(ditridecyl)phosphate titanate,bis(dioctylpyrophosphate)oxyacetate titanate,bis(dioctylpyrophosphate)ethylene titanate or the like.

As the aluminate-based coupling agents, there may be exemplifiedacetoalkoxyaluminum diisopropilate,aluminumdiisopropoxymonoethylacetoacetate,aluminumtrisethylacetoacetate, aluminumtrisacetylacetonate or the like.

As the zirconate-based coupling agents, there may be exemplifiedzirconiumtetrakisacetylacetonate, zirconiumdibutoxybisacetylacetonate,zirconiumtetrakisethylacetoacetate,zirconiumtributoxymonoethylacetoacetate,zirconiumtributoxyacetylacetonate or the like.

It is preferred to use oligomer compounds having a molecular weight offrom 300 to less than 10,000. It is more preferred to use polymercompounds having a molecular weight of 10,000 to about 100,000. In theconsideration of forming a uniform coating layer on the inorganiccompound particles, the oligomers or polymer compounds are preferably ina liquid state, or soluble in water or various solvents.

Examples of the organic pigments used in the present invention mayinclude various organic pigments ordinarily used as colorants of paintsand resin compositions, such as organic red-based pigments, organicblue-based pigments, organic yellow-based pigments, organic green-basedpigments, organic orange-based pigments, organic brown-based pigments,organic violet-based pigments and organic black-based pigments.

Among various organic pigments mentioned above, specific examples of theorganic red-based pigments may include quinacridon pigments such asquinacridon red, azo-based pigments such as permanent red, condensed azopigments such as condensed azo red, condensed polycyclic pigment such asdiketo-pyrrolo-pyrrole, perylene red or the like; specific examples ofthe organic blue-based pigments may include phthalocyanine-basedpigments such as metal-free phthalocyanine blue, phthalocyanine blue andfast sky blue, alkali blue; specific examples of the organicyellow-based pigments may include monoazo-based pigments such as Hanzayellow, disazo-based pigments such as benzidine yellow and permanentyellow, condensed azo pigments such as condensed azo yellow, condensedpolycyclic pigment such as isoindolinone yellow, isoindoline yellow, orthe like; specific examples of the organic green-based pigments mayinclude phthalocyanine-based pigments such as phthalocyanine green, orthe like; and specific examples of the organic black-based pigments mayinclude aniline black, perylene black or the like.

The gluing agent coat may be formed on the surface of the inorganiccompound particles by mechanically mixing and stirring the inorganiccompound particles with the gluing agent or a solution of the gluingagent, or by mechanically mixing and stirring the inorganic compoundparticles while spraying the gluing agent or a solution of the gluingagent thereonto. Substantially whole amount of the gluing agent added isadhered on the surface of the inorganic compound particles for formingthe gluing agent coat thereon.

Meanwhile, in the case where alkoxysilanes or fluoroalkylsilanes areused as the gluing agent, a part of the alkoxysilanes orfluoroalkylsilanes adhered may be coated in the form of organosilanecompounds obtainable from the alkoxysilanes or fluorine-containingorganosilane compounds obtainable from the fluoroalkylsilanes, throughthe coating step. In any of these cases, subsequent adhesion of theorganic pigments on the gluing agent coat is not adversely affected.

In order to uniformly adhere the gluing agent over the surface of theinorganic compound particles, it is preferred that the agglomeratedinorganic compound particles are previously deaggregated using apulverizer.

As the apparatuses for mixing and stirring the inorganic compoundparticles with the gluing agent, or mixing and stirring the organicpigments with the gluing agent-coated inorganic compound particles,there may be used those apparatuses capable of applying a shear force toa layer composed of these particles, in particular, such apparatusescapable of effecting shear action, spatula stroking and compression atthe same time. Examples of such apparatuses may include wheel-typekneaders, ball-type kneaders, blade-type kneaders, roll-type kneaders orthe like. Among these apparatuses, the wheel-type kneaders can be moreeffectively used in the present invention.

Specific examples of the wheel-type kneaders may include edge runners(similar in meaning to mix muller, Simpson mill and sand mill),multimill, Stotz mill, Wet pan mill, corner mill, ring muller or thelike. Among these kneaders, preferred are edge runners, multimill, Stotzmill, Wet pan mill and ring muller, and more preferred are edge runners.

Specific examples of the ball-type kneaders may include vibration millor the like. Specific examples of the blade-type kneaders may includeHenschel mixer, planetary mixer, Nauter mixer or the like. Specificexamples of the roll-type kneaders may include extruders or the like.

The conditions of the mixing and stirring treatment may be selected soas to uniformly coat the surface of the inorganic compound particleswith the gluing agent. Specifically, the mixing and stirring conditionsmay be appropriately controlled such that the linear load is usually19.6 to 1,960 N/cm (2 to 200 Kg/cm), preferably 98 to 1,470 N/cm (10 to150 Kg/cm), more preferably 147 to 980 N/cm (15 to 100 Kg/cm); thetreating time is usually 5 minutes to 24 hours, preferably 10 minutes to20 hours; and the stirring speed is usually 2 to 2,000 rpm, preferably 5to 1,000 rpm, more preferably 10 to 800 rpm.

The amount of the gluing agent added is preferably 0.15 to 45 parts byweight based on 100 parts by weight of the inorganic compound particles.When the gluing agent is added in an amount of 0.15 to 45 parts byweight, it is possible to adhere 1 to 500 parts by weight of the organicpigment based on 100 parts by weight of the inorganic compoundparticles.

After the surface of the inorganic compound particles is coated with thegluing agent, the organic pigment is added, and then mixed and stirredwith the coated inorganic compound particles to adhere the organicpigment onto the gluing agent-coating layer. The obtained particles maybe further subjected to drying or heating treatments, if required.

The amount of the organic pigments added is usually 1 to 500 parts by 510 to 300 parts by weight based on 100 parts by weight of the inorganiccompound particles.

It is preferred that the organic pigments are gradually added little bylittle for a period of preferably about 5 minutes to about 24 hours,more preferably about 5 minutes to about 20 hours, or the organicpigments of 5 to 25 parts by weight based on 100 parts by weight of theinorganic compound particles are intermittently added until reaching thedesired total amount thereof.

The mixing and stirring conditions may be appropriately selected so asto form a uniform organic pigment coat on the gluing agent-coatinglayer, and may be controlled such that the linear load is usually 19.6to 1,960 N/cm (2 to 200 Kg/cm), preferably 98 to 1,470 N/cm (10 to 150Kg/cm), more preferably 147 to 980 N/cm (15 to 100 Kg/cm); the treatingtime is usually 5 minutes to 24 hours, preferably 10 minutes to 20hours; and the stirring speed is usually 2 to 2,000 rpm, preferably 5 to1,000 rpm, more preferably 10 to 800 rpm.

The heating temperature used upon the drying and heating treatments isusually 40 to 150° C., preferably 60 to 120° C. The heating time isusually from 10 minutes to 12 hours, preferably from 30 minutes to 3hours.

Meanwhile, when alkoxysilanes or fluoroalkylsilanes are used as thegluing agent, a coating layer comprising organosilane compoundsobtainable from the alkoxysilanes or fluorine-containing organosilanecompounds obtainable from the fluoroalkylsilanes, is finally formed onthe respective inorganic compound particles via these treatment steps.

The obtained composite particles have an average particle diameter ofusually 0.001 to 0.50 μm, preferably 0.005 to 0.40 μm, more preferably0.01 to 0.30 μm; and a BET specific surface area value of usually 1.0 to500 m²/g, preferably 1.5 to 400 m²/g, more preferably 2.0 to 300 m²/g.

The degree of desorption of the organic pigments from the surface of thecomposite particles is preferably the rank 5 or 4, more preferably therank 5 when visually observed and evaluated by the below-mentionedmethod. When the degree of desorption of the organic pigments is therank 1, 2 or 3, the desorbed organic pigments tend to be re-crystallizedor agglomerated to form coarse particles, thereby causing such adisadvantage that the re-crystallized or agglomerated particles in theform of coarse particles are mixed in the fine coloring particles as afinal product.

The composite particles are then treated with acids or alkalis todissolve out the inorganic compound particles as core particles only orboth of the inorganic compound particles and the gluing agent therefrom.

The acids or alkalis used for the dissolution treatment may beappropriately selected according to kinds of inorganic compoundparticles used. Examples of the acids may include hydrochloric acid,sulfuric acid, oxalic acid, acetic acid, aqueous carbonic acid solution,hydrofluoric acid or the like. Examples of the alkalis may include anaqueous sodium hydroxide solution, ammonia or the like.

Upon the dissolution treatment, the concentration of the compositeparticles contained in the dissolving solution is usually 1.0 to 25.0parts by weight, preferably 2.5 to 20.0 parts by weight, more preferably5.0 to 15.0 parts by weight based on 100 ml of the dissolving solution.

The acid or alkali concentration (mol/liter) of the dissolving solutionused upon the dissolution treatment may be not less than thestoichiometric amount capable of dissolving the inorganic compoundparticles. When the acid or alkali concentration is less than thestoichiometric amount, the inorganic compound particles cannot becompletely dissolved, thereby failing to obtain the fine coloringparticles aimed by the present invention. In the consideration oftreating time and treating temperature, the acid or alkali concentrationof the dissolving solution is preferably not less than 1.1 times thestoichiometric amount, more preferably not less than 1.2 times thestoichiometric amount.

The reaction temperature upon the dissolution treatment is usually 20 to100° C., preferably 20 to 80° C. When the reaction temperature is lessthan 20° C., it takes a long time to dissolve the inorganic compoundparticles, resulting in industrially disadvantageous process. When thereaction temperature is more than 100° C., special apparatuses such asautoclave are required for the dissolution treatment, also resulting inindustrially disadvantageous process.

The terminal point of the dissolution treatment is determined asfollows. That is, the reaction solution during the dissolution treatmentis successively sampled and each sampled solution is separated byfiltration into solid and the dissolving solution. The obtained solid isadded to a fresh dissolving solution for dissolution treatment thereof.Then, the obtained solution is separated by filtration into solid andthe dissolving solution. The obtained solution as filtrate is analyzedby an inductively coupled high-frequency plasma atomic emissionspectroscope. The sampling point at which metal elements constitutingthe core particles of the composite particles are no longer detectedfrom the filtrate, is determined to be the terminal point.

By subjecting the composite particles to such a dissolution treatment,it is possible to obtain hollow particles composed of organic pigmentswhich can still retain a similar shape to that of the inorganic compoundparticles, and/or much finer particles composed of the organic pigments,which no longer retain the similar shape due to breaking of the hollowparticles.

After the dissolution treatment, the obtained solution is separated byfiltration into solid and the dissolving solution, and the thus obtainedsolid is freeze-dried, thereby obtaining fine coloring particles as thefunctional material.

Next, the process for producing the dispersion according to the presentinvention is described.

The water-based dispersion of the present invention is produced byre-dispersing the fine coloring particles as the functional materialwhich are obtained by the freeze-drying process, in water or a mixtureof water and a water-soluble organic solvent, or by separating thesolution obtained after the dissolution treatment into solid and thedissolving solution by means of filtration, washing the obtained solidwith water, and then dispersing the solid in water or a mixture of waterand a water-soluble organic solvent. If required, various additives suchas resins, defoaming agents, surfactants, etc., may be added to thewater-based dispersion.

The solvent-based dispersion of the present invention is produced byre-dispersing the fine coloring particles as the functional materialwhich are obtained by the freeze-drying process, in an organic solventor an oily vehicle, or by separating the solution obtained after thedissolution treatment into solid and the dissolving solution by means offiltration, washing the obtained solid with water, flashing the obtainedpaste-like solid with the organic solvent or the oily vehicle, and thendispersing the paste-like solid in the organic solvent or the oilyvehicle. If required, various additives such as resins, surfactants,etc., may be added to the solvent-based dispersion.

The functional material composed of the fine coloring particlesaccording to the present invention can be used as colorants for resincompositions, ink-jet printing inks, paints, printing inks, etc.

The resin composition according to the present invention comprises thefunctional material composed of the fine coloring particles and knownthermoplastic resins as well as, if required, additives such aslubricants, plasticizers, antioxidants, ultraviolet light absorbers,various stabilizers or the like.

The amount of the functional material composed of the fine coloringparticles blended in the resin composition of the present invention isin the range of usually 0.01 to 200 parts by weight based on 100 partsby weight of resins contained in the resin composition. In theconsideration of handling property of the resin composition, the amountof the functional material composed of the fine coloring particlesblended therein is preferably 0.05 to 150 parts by weight, morepreferably 0.1 to 100 parts by weight based on 100 parts by weight ofthe resins.

Examples of the reins may include thermoplastic resins, e.g.,polyolefins such as polyethylene, polypropylene, polybutene andpolyisobutylene, polyvinyl chloride, polymethyl pentene, polyethyleneterephthalate, polybutylene terephthalate, polystyrene, styrene-acrylicacid ester copolymers, styrene-vinyl acetate copolymers,acrylonitrile-butadiene-styrene copolymers, acrylonitrile-EPDM-styrenecopolymers, acrylic resins, polyamides, polycarbonates, polyacetal andpolyurethane; rosin-modified maleic acid resins; phenol resins; epoxyresins; polyester resins; silicone resins; rosin esters; rosins; naturalrubbers, synthetic rubbers; or the like.

The resin composition tinted with the functional material composed ofthe fine coloring particles according to the present invention exhibitsa dispersing condition of usually the rank 4 or 5, preferably the rank 5when visually observed and evaluated by the below-mentioned method; anda light transmittance of usually not less than 80%, preferably not lessthan 85%.

Next, the ink-jet printing ink containing the functional materialcomposed of the fine coloring particles according to the presentinvention is described.

The ink-jet printing ink according to the present invention comprisesthe functional material composed of the fine coloring particlesaccording to the present invention and as an ink base solution, adispersant, water, and, if required, a penetrant, a humectant, awater-soluble solvent, a pH modifier, a preservative or the like.

The amount of the functional material composed of the fine coloringparticles contained in the ink-jet printing ink is usually 1 to 20% byweight based on the weight of the ink base solution. The amount of thedispersant contained in the ink-jet printing ink is preferably 5 to 200%by weight, more preferably 7.5 to 150% by weight based on the weight ofthe functional material as pigments contained in the ink-jet printingink.

As the dispersant, there may be used high-molecular dispersants and/orsurfactants such as surfactant may include anionic surfactants, nonionicsurfactants and cationic surfactants. In the consideration of the effectof improving the dispersibility of the functional material in theink-jet printing ink and good dispersion stability of the obtained ink,anionic surfactants and nonionic surfactants are preferably used as thesurfactant, and water-soluble resins such as styrene-acrylic acidcopolymers are preferably used as the high-molecular dispersant.

Specific examples of the preferred anionic surfactants may include fattyacid salts, sulfuric acid esters, sulfonic acid salts, phosphoric acidesters or the like. Among these anionic surfactants, sulfuric acidesters and sulfonic acid salts are more preferred.

Specific examples of the preferred nonionic surfactants may includepolyethylene glycol-type nonionic surfactants such as polyoxyethylenealkyl ethers and polyoxyethylene aryl ethers; polyhydric alcohol-typenonionic surfactants such as sorbitan fatty acid esters; or the like.Among these nonionic surfactants, polyethylene glycol-type nonionicsurfactants are more preferred.

Specific examples of the preferred cationic surfactants may includeamine salt-type cationic surfactants, quaternary ammonium salt-typecationic surfactants or the like. Among these cationic surfactants, thequaternary ammonium salt-type cationic surfactants are more preferred.

As the polymeric dispersing agent, there may be used alkali-solubleresins such as styrene-acrylic acid copolymers, styrene-maleic acidcopolymers, polyacrylic acid derivatives or the like.

As the solvent for the ink-jet printing ink, water may be used, ifrequired, in combination with a water-soluble organic solvent. Theamount of the water-soluble organic solvent contained in the ink-jetprinting ink is usually 1 to 50% by weight, preferably 1 to 40% byweight, more preferably 1 to 30% by weight based on the weight of theink base solution.

Examples of the water-soluble organic solvent for the ink-jet printingink may include monohydric alcohols such as methanol, ethanol,n-propanol and isopropanol; dihydric alcohols such as ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol, propyleneglycol and dipropylene glycol; trihydric alcohols such as glycerol;polyalkylene glycols such as polyethylene glycol; lower alkyl ethers ofpolyhydric alcohols such as propylene glycol monomethyl ether, propyleneglycol monoethyl ether, ethylene glycol monopropyl ether, diethyleneglycol monobutyl ether, ethylene glycol monobutyl ether and ethyleneglycol monoethyl ether; or the like. Among these water-soluble organicsolvents, dihydric alcohols are preferred. These water-soluble organicsolvents may be used alone or in the form of a mixture of any two ormore thereof.

The functional material composed of the fine coloring particlescontained in the ink-jet-printing ink of the present invention has adispersed particle diameter of preferably not more than 0.2 μm, morepreferably not more than 0.1 μm. The dispersion stability of the ink-jetprinting ink of the present invention is preferably the rank 4 or 5,more preferably the rank 5 when visually observed and evaluated by thebelow-mentioned method. The percentage of change in dispersed particlediameter is preferably not more than 10%, more preferably not more than8%.

The point of the present invention is that the functional materialcomposed of the fine coloring particles according to the presentinvention can exhibit not only an excellent transparency, but also ahigh tinting strength and a clear hue.

The reason why the functional material composed of the fine coloringparticles according to the present invention can exhibit an excellenttransparency, is considered as follows. That is, since the organicpigments which generally tend to be agglomerated and, therefore, act assecondary particles, are formed into fine coloring particles having anaverage primary particle diameter as small as not more than 50 nm in adried state, the light-scattering coefficient thereof can beconsiderably reduced.

The reason why the functional material composed of the fine coloringparticles according to the present invention can exhibit a clear hue, isconsidered as follows, though not clearly determined yet. That is,organic pigments usually tend to undergo undesirable crystal growth atrespective stages of synthesis thereof due to their specific crystalstructure, so that it may be difficult to attain a uniform crystal size.As a result, absorption peak at the wavelength inherent to each colorbecomes broad. Whereas, in the case of the functional material composedof the fine coloring particles according to the present invention, sincethe particle size thereof can be reduced to near molecular level similarto dyes, it is considered that the absorption peak at the wavelengthinherent to each color becomes much sharper.

The functional material composed of the fine coloring particlesaccording to the present invention, is in the form of fine coloringparticles, and can exhibit not only an excellent transparency, but alsoa high tinting strength and a clear hue. Therefore, the functionalmaterial can be suitably used as a colorant.

Thus, the functional material composed of the fine coloring particlesaccording to the present invention can exhibit the above excellentproperties and, therefore, can be suitably used as colorants for resincompositions, ink-jet printing inks, paints and printing inks.

EXAMPLES

The present invention is described in more detail by Examples andComparative Examples, but the Examples are only illustrative and,therefore, not intended to limit the scope of the present inventionthereto.

Various properties were measured by the following methods.

(1) The average primary particle diameter of the particles was expressedby the average value of measured particle diameters of 350 particlesobserved on an electron micrograph (×50,000).

(2) The average particle diameter of the secondary Particles(flocculate) of the functional material was expressed by the averagevalue of particle diameters obtained by following method. The particlediameter of the secondary particles (flocculate) contained in thedispersion obtained by mixing the secondary particles (flocculate) withwater and dispersing the secondary particles (flocculate) in water forone minute using an ultrasonic dispersing apparatus, was measured by adynamic light scattering method using a concentration-type particle sizeanalyzer “FPAR-1000” manufactured by Ohtsuka Denshi Co., Ltd.

(3) The specific surface area was expressed by the value measured by aBET method.

(4) The amounts of the gluing agent-coating layer formed on the surfaceof the inorganic compound particles, and the organic pigment coat formedon the gluing agent-coating layer were respectively determined bymeasuring the carbon contents using “Horiba Metal, Carbon and SulfurAnalyzer EMIA-2200 Model” (manufactured by HORIBA SEISAKUSHO CO., LTD.).

(5) The hue of each of the organic pigment and functional material, weremeasured by the following method.

That is, 0.5 g of each sample and 0.5 ml of castor oil were intimatelykneaded together by a Hoover's muller to form a paste. 4.5 g of clearlacquer was added to the obtained paste and was intimately kneaded toform a paint. The obtained paint was applied on a clear film by using a150 μm (6-mil) applicator to produce a coating film piece (having a filmthickness of about 30 μm). The thus obtained coating film piece wasmeasured by a multi-spectro-colour-meter “MSC-IS-2D” (manufactured bySUGA TESTING MACHINES MANUFACTURING CO., LTD.) to determine L*, a* andb* values thereof, respectively. Meanwhile, the C* value representingchroma is calculated according to the following formula:

C*=((a*)²+(b*)²)^(1/2)

(6) The tinting strength of the functional material was measured by thefollowing method.

That is, a primary color enamel and a vehicle enamel prepared by thebelow-mentioned method were respectively applied on a cast-coated paperby a 150 μm (6-mil) applicator to produce coating film pieces. The thusobtained coating film pieces were measured by amulti-spectro-colour-meter “MSC-IS-2D” (manufactured by SUGA TESTINGMACHINES MANUFACTURING CO., LTD.) to determine L* values thereof. Thedifference between the obtained L* values was represented by a ΔL*value.

Next, as a standard sample, using the organic pigment used for theproduction of the functional material, the same procedure as definedbelow was conducted to prepare an primary color enamel and a vehicleenamel, form coating film pieces and measure L* values thereof. Thedifference between the L* values was represented by a ΔLs* value.

From the obtained ΔL* value of the colorant and ΔLs* value of thestandard sample, the tinting strength (%) was calculated according tothe following formula:

Tinting strength(%)=100+{(ΔLs*−ΔL*)×10}

Preparation of Primary Color Enamel:

10 g of the above sample particles, 16 g of an amino alkyd resin and 6 gof a thinner were blended together. The resultant mixture was addedtogether with 90 g of 3 mmφ glass beads into a 140-ml glass bottle, andthen mixed and dispersed for 45 minutes by a paint shaker. The obtainedmixture was mixed with 50 g of an amino alkyd resin, and furtherdispersed for 5 minutes by a paint shaker, thereby obtaining an primarycolor enamel.

Preparation of Vehicle Enamel:

12 g of the above-prepared primary color enamel and 40 g of Amirac White(titanium dioxide-dispersed amino alkyd resin) were blended together,and the resultant mixture was mixed and dispersed for 15 minutes by apaint shaker, thereby preparing a vehicle enamel.

(7) The light transmittance of the functional material composed of finecoloring particles was measured by the following method:

(i) blending 5 g of the functional material (fine coloring particles)and the following components as a paint base material at thebelow-mentioned mixing ratio in a 250 ml glass bottle, and mixing anddispersing the resultant mixture together with 160 g of 3 mmφ glassbeads using a paint shaker for 120 minutes, thereby preparing a paint:

Functional material  9.9 parts by weight Melamine resin 19.8 parts byweight Alkyd resin 39.6 parts by weight Xylene 29.7 parts by weightButanol  1.0 part by weight;

(ii) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and

(iii) measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer in which the light transmittance (%) is expressed bythe highest peak value. The closer to 100% the light transmittance, thehigher the transparency.

Meanwhile, when measuring the light transmittance values thereof, theclear film was used as blank.

(8) The decree of desorption of the organic pigments from the compositeparticles was evaluated by the following method, and the evaluationresults were classified into the following five ranks. The rank 5represents that the amount of the organic pigments desorbed from thesurface of the composite particles was smallest.

That is, 2 g of the particles to be measured and 20 ml of ethanol wereplaced in a 50-ml conical flask, and then subjected to ultrasonicdispersion for 60 minutes. Thereafter, the obtained dispersion wascentrifuged at a rotating speed of 10,000 rpm for 15 minutes to separatethe dispersion into the particles and the ethanol solvent. The obtainedparticles were dried at 80° C. for one hour, and the micrograph(×50,000) thereof was visually observed to count the number of thedesorbed and re-agglomerated organic pigment particles which werepresent in a visual field of the micrograph. The micrograph was comparedwith a micrograph (×50,000) of mixed particles obtained by simply mixingthe inorganic compound particles with the organic pigments withoutforming the intermediate gluing agent coat. The evaluation results wereclassified into the following five ranks.

-   -   Rank 1: Number of desorbed particles was substantially the same        as that in the simply mixed particles;    -   Rank 2: 30 to 49 desorbed particles per 100 composite particles        were recognized;    -   Rank 3: 10 to 29 desorbed particles per 100 composite particles        were recognized;    -   Rank 4: 5 to 9 desorbed particles per 100 composite particles        were recognized; and    -   Rank 5: 0 to 4 desorbed particles per 100 composite particles        were recognized.

(9) The light transmittance of the dispersion containing the functionalmaterial composed of the fine coloring particles was measured by thefollowing method. Namely, an aqueous solution containing 0.04% by weightof the functional material composed of the fine coloring particles inthe case of the water-based dispersion, and a toluene solutioncontaining 0.04% by weight of the functional material composed of thefine coloring particles in the case of the solvent-based dispersion,were respectively placed in a quartz cell, and the light transmittancethereof was measured in a wavelength region of 380 to 700 nm using aself-recording photoelectric spectrophotometer. The light transmittance(%) was expressed by the highest measured value.

Meanwhile, when measuring the light transmittance values of thedispersions, ion-exchanged water and toluene were used as blanks for thewater-based dispersion and the solvent-based dispersion, respectively.

(10) The hue of the resin composition tinted with the functionalmaterial composed of the fine coloring particles was measured by thefollowing method. That is, a colored resin plate prepared by thebelow-mentioned method was measured by a multi-spectro-colour-meter“MSC-IS-2D” (manufactured by SUGA SHIKENKI CO., LTD.) to determine L*,a* and b* values thereof.

(11) The light transmittance of the resin composition containing thefunctional material composed of the fine coloring particles was measuredby the following method. Namely, the light transmittance of a coloredresin plate prepared by the below-mentioned method was measured in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer. The light transmittance (%) was expressed by thehighest measured value.

Meanwhile, when measuring the light transmittance value of the resincomposition, a resin composition containing no fine coloring particleswas used as a blank.

(12) The dispersibility of the resin composition tinted with thefunctional material composed of the fine coloring particles wasevaluated by visually counting the number of undispersed aggregateparticles on the surface of the obtained colored resin plate, andclassifying the evaluation results into the following five ranks. Therank 5 represents the most excellent dispersing condition.

-   -   Rank 5: No undispersed aggregate particles were recognized.    -   Rank 4: 1 to 4 undispersed aggregate particles per 1 cm² were        recognized;    -   Rank 3: 5 to 9 undispersed aggregate particles per 1 cm² were        recognized;    -   Rank 2: 10 to 49 undispersed aggregate particles per 1 cm² were        recognized;    -   Rank 1: Not less than 50 undispersed aggregate particles per 1        cm² were recognized.

(13) The dispersed particle diameter of particles contained in thedispersion and the ink-jet printing ink was measured by aconcentration-type particle size analyzer “FPAR-1000” manufactured byOhtsuka Denshi Co., Ltd.

(14) The dispersion stability of the dispersion and the ink-jet printingink was evaluated as follows. That is, 25 ml of the dispersion or theink-jet printing ink to be measured was placed in a color comparisontube, and allowed to stand at 60° C. for one week. Then, the degree ofprecipitation of the particles contained in the dispersion or theink-jet printing ink was visually observed and evaluated. Theobservation results were classified into the following five ranks.

-   -   Rank 1: Length of uncolored portion was not less than 10 cm;    -   Rank 2: Length of uncolored portion was from 5 cm to less than        10 cm;    -   Rank 3: Length of uncolored portion was from 1 cm to less than 5        cm;    -   Rank 4: Length of uncolored portion was less than 1 cm;    -   Rank 5: Uncolored portion was not recognized.

(15) The percentage of chance in dispersed particle diameter ofparticles contained in the dispersion and the ink-jet printing ink wasdetermined as follows. That is, after the dispersion or the ink to bemeasured was allowed to stand at 60° C. for one week, the dispersedparticle diameter of particles contained therein was measured by theabove concentration-type particle size analyzer “FPAR-1000” manufacturedby Ohtsuka Denshi Co., Ltd. The percentage of change in dispersedparticle diameter was expressed by the value (%) obtained by dividingthe amount of change in dispersed particle diameter between before andafter the standing test by the dispersed particle diameter measuredbefore the standing test.

Example 1 Production of Functional Material

140 g of methyl hydrogen polysiloxane (tradename: “TSF484”, produced byGE TOSHIBA SILICONE CO., LTD.) was added to 7.0 kg of silica particles(particle shape: spherical shape; average particle diameter: 0.021 μm;BET specific surface area value: 196.2 m²/g) while operating an edgerunner, and the resultant mixture was mixed and stirred for 30 minutesunder a linear load of 588 N/cm (60 kg/cm) at a stirring speed of 22rpm.

Then, 7.0 kg of organic pigments B (kind: phthalocyanine-based pigments;particle shape: granular shape; average particle diameter: 0.06 μm; BETspecific surface area value: 71.6 m²/g; light transmittance: 71.0%; L*value: 17.70; a* value: 9.72; b* value: −23.44; C* value: 25.38) wereadded to the above-obtained mixture for 100 minutes while operating theedge runner, and the resultant mixture was mixed and stirred for 120minutes under a linear load of 588 N/cm (60 kg/cm) at a stirring speedof 22 rpm, thereby adhering the organic pigments B onto the methylhydrogen polysiloxane coating layer formed on the surface of the silicaparticles. The obtained particles were dried at 80° C. for 60 minutesusing a dryer, thereby obtaining composite particles.

It was confirmed that the thus obtained composite particles were in theform of granular particles having an average particle diameter of 0.025μm, and had a BET specific surface area value of 86.2 m²/g, an organicpigment desorption degree of Rank 5, and a coating amount of methylhydrogen polysiloxane of 0.52% by weight (calculated as C), and that theamount of the organic pigments B adhered was 33.21% by weight(calculated as C; corresponding to 100 parts by weight based on 100parts by weight of the silica particles).

As a result of observing the micrograph of the obtained compositeparticle since almost no organic pigments B were recognized from themicrograph, it was confirmed that a substantially whole amount of theorganic pigments B used contributed to the formation of the organicpigment coat on the coating layer composed of methyl hydrogenpolysiloxane. Further, it was confirmed that the organic pigments Badhered no longer maintained the particle shape and size of thoseinitially added, more specifically, the organic pigments B had a muchfiner particle size than that of the inorganic compound particles andwere adhered in the form of a uniform adhesion coat on the surface ofthe inorganic compound particles.

A 1-liter plastic beaker was charged with 50.0 g of the above obtainedcomposite particles and 500 ml of a 5.5 mol/l hydrofluoric acid aqueoussolution (1.7 times the stoichiometric amount capable of dissolving thesilica particles as core particles), and the contents of the beaker werestirred at 25° C. for 60 minutes. The resultant mixture was filtered andwashed with water, thereby obtaining a paste of fine coloring particles.The paste of fine coloring particles was re-dispersed in ion-exchangedwater, and then freeze-dried, thereby obtaining fine coloring particles.

It was conformed that the obtained fine coloring particles had anaverage primary particle diameter thereof in a dried state of 6 nm, anaverage particle diameter of the flocculate thereof of 21 nm, a BETspecific surface area value of 178.8 m²/g, a light transmittance of92.1% and a tinting strength of 139%. As to the hue of the fine coloringparticles, the L* value thereof was 18.14; the a* value thereof was11.14; the b* value thereof was −25.64; and the C* value thereof was27.96.

<Production of Water-Based Dispersion>

18.0 g of the paste of functional material (solid content: 6 g) obtainedafter the water-washing, 41.1 g of ion-exchanged water, 0.7 g of adispersant (mixture of polyacrylic acid and styrene-maleic acidcopolymer (=8:2)) and 0.2 g of a defoaming agent (silicone-baseddefoaming agent) were charged together with 150 g of 1.5 mmφ glass beadsinto a 220 ml glass bottle, and then mixed and dispersed for one hourusing a paint shaker, thereby obtaining a water-based dispersion.

It was confirmed that the obtained water-based dispersion containing thefunctional material had a concentration of 10.3% by weight, an averageparticle diameter of 4 nm, a dispersion stability of the rank 5, apercentage of change in dispersed particle diameter of 3.2%, and a lighttransmittance of 94%.

<Production of Solvent-Based Dispersion>

The paste of functional material obtained after the water-washing wascharged into a kneader, and kneaded with toluene at the following mixingratio. After removing separated water, the kneader was closed, and theinside pressure thereof was reduced to about 30 mmHg while heating to60° C. to remove water therefrom, thereby obtaining a solvent-baseddispersion.

Paste of functional material 100 parts by weight (solid content: 40% byweight) Solvent (toluene)  60 parts by weight

It was confirmed that the obtained solvent-based dispersion containingthe fine coloring particles had a concentration of 66.5% by weight and alight transmittance of 80.6%.

Use Example 1 Production of Resin Composition

0.5 g of the fine coloring particles and 49.5 g of polyvinyl chlorideresin particles (“103EP8D” (tradename), produced by NIPPON ZEON CO.,LTD.) were weighed and charged into a 100 ml plastic beaker, andintimately mixed together by a spatula, thereby obtaining mixedparticles.

1.0 g of calcium stearate was added to the obtained mixed particles. Theresultant mixture was intimately mixed and then slowly supplied to hotrolls heated to 160° C. whose clearance was set to 0.2 mm, andcontinuously kneaded therebetween until a uniform resin composition wasproduced. The resin composition kneaded was separated from the hot rollsand used as a raw material for forming a colored resin plate. Next, thethus-produced resin composition was interposed between a pair ofsurface-polished stainless steel plates, placed within a hot pressheated to 180° C. and then subjected to a pressure molding whileapplying a pressure of 98,000 kPa (1 ton/cm²) thereto, thereby obtaininga colored resin plate having a thickness of 1 mm.

It was confirmed that as to the hue of the obtained colored resin plate,the L* value thereof was 19.51, the a* value thereof was 9.54, the b*value thereof was −25.68, and the C* value thereof was 27.39, and thatthe colored resin plate had a dispersing condition of the rank 5 and alight transmittance of 92%.

Use Example 2 Production of Ink-Jet Printing Ink

The water-based dispersion and the following raw materials were mixedwith each other under stirring, and the resultant mixture was filteredusing a 0.5 μm membrane filter, thereby obtaining an ink-jet printingink.

Water-based dispersion 10.0 parts by weight  Diethylene glycol 2.0 partsby weight Ion-exchanged water 8.0 parts by weight

It was confirmed that the obtained ink-jet printing ink had a dispersedparticle diameter in ink of 20 nm, a dispersion stability by visualobservation of the rank 5, and a percentage of change in dispersedparticle diameter of 2.5%. As to the hue of the ink-jet printing ink,the L* value thereof was 19.13, the a* value thereof was 9.08, the b*value thereof was −24.48, and the C* value thereof was 26.11.

<Inorganic Compound Particles>

Inorganic compound particles 1 to 4 having properties shown in Table 1were prepared.

<Organic Pigments>

Organic pigments having properties shown in Table 2 were prepared.

<Production of Composite Particles> Composite Particles 1 to 4:

The same procedure as defined in Example 1 was conducted except thatkinds of inorganic compound particles, kinds and amounts of gluing agentadded, linear load and treating time used in the coating step withgluing agent, kinds and amounts of organic pigments adhered, and linearload and treating time used in organic pigment-adhering step werechanged variously, thereby obtaining composite particles.

The essential production conditions are shown in Table 3, and variousproperties of the obtained composite particles are shown in Table 4.

Examples 2 to 4 and Comparative Examples 1 and 2 Production ofFunctional Material

The same procedure as defined in Example 1 was conducted except thatkinds of composite particles, kind and amount of dissolving solution,and dissolution treatment temperature were changed variously, therebyobtaining a functional material. Meanwhile, the amount of the compositeparticles added is expressed by “part by weight” based on 100 ml of thedissolving solution.

The essential production conditions are shown in Table 5, and variousproperties of the obtained functional material are shown in Table 6.

Examples 5 to 10 and Comparative Examples 3 to 8 Dispersion ContainingFunctional Material

The same procedure as defined in Example 1 was conducted except thatkinds of functional material, and kinds and amounts of solvents added aswater-based pigment dispersion base material, were changed variously,thereby obtaining dispersions.

The essential production conditions and various properties of theobtained dispersions containing the functional material are shown inTable 7.

Use Examples 3 to 5 and Comparative Use Examples 1 to 6 ResinComposition

The same procedure as defined in Use Example 1 was conducted except thatkinds of functional material were changed variously, thereby obtainingresin compositions.

The essential production conditions and various properties of theobtained resin compositions are shown in Table 8.

Use Examples 6 to 8 and Comparative Use Examples 7 to 12 Production ofInk-Jet Printing Ink

The same procedure as defined in Use Example 2 was conducted except thatkinds of dispersions containing functional material were changedvariously, thereby obtaining ink-jet printing inks.

The essential production conditions and various properties of theobtained ink-jet printing inks are shown in Table 9.

TABLE 1 Properties of inorganic compound particles BET specific Averagesurface particle area Core diameter value particles Kind Shape (μm)(m²/g) Core Magnetite Spherical 0.230 11.8 particles 1 Core Zinc oxideGranular 0.183 18.3 particles 2 Core Calcium Granular 0.140 18.6particles 3 carbonate Core Silica Granular 0.021 196.2 particles 4

TABLE 2 Properties of organic pigments Average particle Organic diameterpigments Kind Shape (μm) Organic Pigment Blue Granular 0.06 pigments B(phthalocyanine- based pigment) Organic Pigment Green Granular 0.06pigments G (phthalocyanine- based pigment) Organic Pigment Red Granular0.58 pigments R (quinacridone- based pigment) Organic Pigment YellowGranular 0.73 pigments Y (azo-based pigment) Properties of organicpigments BET specific Organic surface area value Light transmittancepigments (m²/g) (%) Organic 71.6 71.0 pigments B Organic 60.5 59.7pigments G Organic 19.3 74.9 pigments R Organic 10.5 34.5 pigments YProperties of organic pigments Hue Organic L* value a* value b* value C*value pigments (—) (—) (—) (—) Organic 17.70 9.72 −23.44 25.38 pigmentsB Organic 21.83 −18.31 −7.36 19.73 pigments G Organic 36.99 51.88 20.5755.81 pigments R Organic 66.80 0.78 70.92 70.92 pigments Y

TABLE 3 Production of composite particles Coating step with glutingagent Additives Amount Kind of added Composite core (wt. particlesparticles Kind part) Composite Core Methyl 6.0 particles 1 particles 1triethoxysilane Composite Core Polyvinyl alcohol 5.0 particles 2particles 2 Composite Core γ-aminopropyl 2.0 particles 3 particles 3triethoxysilane Composite Core Methyl 0.005 particles 4 particles 4triethoxysilane Production of composite particles Coating step withgluing agent Coating amount Edge runner treatment (calculated CompositeLinear load Time as C) particles (N/cm) (Kg/cm) (min) (wt. %) Composite441 45 30 0.38 particles 1 Composite 588 60 20 2.56 particles 2Composite 294 30 20 0.31 particles 3 Composite 588 60 20 3 × 10⁻⁴particles 4 Production of composite particles Adhesion step with organicpigments Organic pigments Composite Amount added particles Kind (wt.part) Composite G 20.0 particles 1 Composite R 30.0 particles 2Composite Y 50.0 particles 3 Composite B 100.0 particles 4 Production ofcomposite particles Adhesion step with organic pigments Amount adheredEdge runner treatment (calculated Composite Linear load Time as C)particles (N/cm) (Kg/cm) (min) (wt. %) Composite 392 40 60 5.94particles 1 Composite 588 60 30 17.61 particles 2 Composite 588 60 6018.77 particles 3 Composite 588 60 60 33.16 particles 4

TABLE 4 Properties of composite particles Degree of Average BET specificdesorption particle surface area of organic Composite diameter valuepigments particles (μm) (m²/g) (—) Composite 0.231 7.6 5 particles 1Composite 0.184 13.6 5 particles 2 Composite 0.142 11.3 5 particles 3Composite 0.021 124.1 2 particles 4

TABLE 5 Production of functional material Examples and Compositeparticles Comparative Amount added Examples Kind (wt. part) Example 2Composite particles 1 10.0 Example 3 Composite particles 2 10.0 Example4 Composite particles 3 10.0 Comparative Particles obtained in 10.0Example 1 Example 1 Comparative Composite particles 4 10.0 Example 2Production of functional material Dissolving solution Ratio to Examplesand stoichiometric Treating Comparative Concentration amount temp.Examples Kind (mol/l) (—) (° C.) Example 2 Oxalic acid 4.5 3.5:1 25Example 3 Hydrochloric 3.0 1.7:1 25 acid Example 4 Hydrochloric 3.03.0:1 25 acid Comparative Hydrofluoric 2.5 0.8:1 25 Example 1 acidComparative Hydrofluoric 5.5 1.7:1 25 Example 2 acid

TABLE 6 Properties of functional material Average primary Averageparticle diameter particle of fine coloring diameter of BET specificExamples and particles in a flocculate surface area Comparative driedstate thereof value Examples (nm) (nm) (m²/g) Example 2 9 38 113.2Example 3 7 29 121.6 Example 4 10 44 131.2 Comparative 109 452 42.7Example 1 Comparative 315 1,107 28.4 Example 2 Properties of functionalmaterial Examples and Hue Comparative L* value a* value b* value C*value Examples (—) (—) (—) (—) Example 2 22.16 −19.64 −8.64 21.46Example 3 38.04 53.64 22.63 58.22 Example 4 68.32 2.68 73.64 73.69Comparative 18.96 8.73 −21.14 22.87 Example 1 Comparative 18.43 8.41−20.52 22.18 Example 2 Examples and Properties of functional materialComparative Tinting strength Light transmittance Examples (%) (%)Example 2 126 92.7 Example 3 128 95.3 Example 4 131 90.5 Comparative 9768.9 Example 1 Comparative 94 65.4 Example 2

TABLE 7 Production of dispersion containing functional material ExamplesFine particles Solvent and Amount Amount Comparative added addedExamples Kind (wt. part) Kind (wt. part) Example 5 Example 2 11.1 Water98.3 Example 6 Example 3 11.1 Water 98.3 Example 7 Example 4 11.1 Water98.3 Example 8 Example 2 66.7 Toluene 100.0 Example 9 Example 3 53.8Toluene 100.0 Example 10 Example 4 100.0 Toluene 100.0 ComparativeOrganic 11.1 Water 98.3 Example 3 pigment B Comparative Organic 11.1Water 98.3 Example 4 pigment G Comparative Organic 11.1 Water 98.3Example 5 pigment R Comparative Organic 11.1 Water 98.3 Example 6pigment Y Comparative Comparative 11.1 Water 98.3 Example 7 Example 1Comparative Comparative 11.1 Water 98.3 Example 8 Example 2 Propertiesof dispersion containing functional Examples material and Dispersedparticle Comparative Concentration diameter Examples (wt. %) (nm)Example 5 10.2 15 Example 6 10.1 12 Example 7 10.1 22 Example 8 67.0 —Example 9 54.2 — Example 10 100.3 — Comparative 10.3 226 Example 3Comparative 10.1 214 Example 4 Comparative 10.2 382 Example 5Comparative 10.1 962 Example 6 Comparative 10.2 312 Example 7Comparative 10.3 218 Example 8 Properties of dispersion containingfunctional material Dispersion stability Percentage of change inExamples dispersed and Visual particle Light Comparative observationdiameter transmittance Examples (—) (%) (%) Example 5 5 3.9 81.2 Example6 5 4.3 83.3 Example 7 4 3.6 80.5 Example 8 — — 81.4 Example 9 — — 83.2Example 10 — — 80.8 Comparative 1 17.8 18.0 Example 3 Comparative 1 18.919.5 Example 4 Comparative 1 17.5 14.8 Example 5 Comparative 1 21.8 13.2Example 6 Comparative 2 12.4 20.3 Example 7 Comparative 1 17.6 22.6Example 8

TABLE 8 Properties of Use Examples Production of resin resin compositionand composition Dispersing Comparative Kind of functional condition UseExamples material (—) Use Example 1 Example 2 5 Use Example 2 Example 35 Use Example 3 Example 4 4 Comparative Organic pigment B 2 Use Example1 Comparative Organic pigment G 2 Use Example 2 Comparative Organicpigment R 2 Use Example 3 Comparative Organic pigment Y 2 Use Example 4Comparative Comparative Example 1 2 Use Example 5 ComparativeComparative Example 2 2 Use Example 6 Properties of resin compositionUse Examples Hue and L* a* b* C* Light Comparative value value valuevalue transmittance Use Examples (—) (—) (—) (—) (%) Use Example 1 24.58−18.36 −7.95 20.01 91.8 Use Example 2 41.17 51.41 21.05 55.55 92.0 UseExample 3 70.94 2.04 71.88 71.91 90.1 Comparative 20.01 10.04 −22.8925.00 70.2 Use Example 1 Comparative 23.56 −17.65 −6.73 18.89 59.3 UseExample 2 Comparative 39.42 50.46 19.60 54.13 73.6 Use Example 3Comparative 69.15 0.67 69.94 69.94 35.2 Use Example 4 Comparative 21.238.03 −20.76 22.26 66.2 Use Example 5 Comparative 21.04 8.21 −20.13 21.7466.9 Use Example 6

TABLE 9 Production of ink-jet printing ink Use Examples Dispersioncontaining functional and material Comparative Amount blended UseExamples Kind (wt. part) Use Example 4 Example 2 10.0 Use Example 5Example 3 10.0 Use Example 6 Example 4 10.0 Comparative Organic pigmentB 10.0 Use Example 7 Comparative Organic pigment G 10.0 Use Example 8Comparative Organic pigment R 10.0 Use Example 9 Comparative Organicpigment Y 10.0 Use Example 10 Comparative Comparative Example 1 10.0 UseExample 11 Comparative Comparative Example 2 10.0 Use Example 12Properties of ink-jet printing ink Dispersion stability Percentage ofchange in Use Examples Dispersed dispersed and particle Visual particleComparative diameter observation diameter Use Examples (nm) (—) (%) UseExample 4 16 5 3.6 Use Example 5 12 5 4.0 Use Example 6 21 5 3.2Comparative 251 1 16.4 Use Example 7 Comparative 243 1 18.0 Use Example8 Comparative 404 1 16.9 Use Example 9 Comparative 980 1 21.1 UseExample 10 Comparative 328 2 12.2 Use Example 11 Comparative 235 2 16.8Use Example 12 Properties of ink-jet printing ink Use Examples Hue andC* Comparative L* value a* value b* value value Use Examples (—) (—) (—)(—) Use Example 4 22.34 −19.41 −8.33 21.12 Use Example 5 38.15 53.0221.94 57.38 Use Example 6 69.27 2.24 72.86 72.89 Comparative 19.54 8.72−21.82 23.50 Use Example 7 Comparative 23.61 −17.18 −5.39 18.01 UseExample 8 Comparative 39.03 49.26 18.47 52.61 Use Example 9 Comparative69.76 0.44 67.58 67.58 Use Example 10 Comparative 19.93 7.23 −20.4121.65 Use Example 11 Comparative 19.72 7.38 −19.96 21.28 Use Example 12

1.-2. (canceled)
 3. A functional material comprising fine coloringparticles having an average primary particle diameter of 1 to 50 nm in adried state, and having a BET specific surface area value of 30 to 500m²/g, a tinting strength of not less than 110% and a light transmittanceof not less than 80% when evaluated by the following method: (1)blending 5 g of the functional material and the following components asa paint base material at the below-mentioned mixing ratio in a 250 mlglass bottle, and mixing and dispersing the resultant mixture togetherwith 160 g of 3 mmφ glass beads using a paint shaker for 120 minutes,thereby preparing a paint: Functional material  9.9 parts by weightMelamine resin 19.8 parts by weight Alkyd resin 39.6 parts by weightXylene 29.7 parts by weight Butanol  1.0 part by weight;

(2) applying the thus prepared paint onto a 100 μm-thick clear film toform a coating film having a thickness of 150 μm thereon; and (3)measuring a light transmittance of the obtained coating film in awavelength region of 380 to 700 nm using a self-recording photoelectricspectrophotometer; produced by a process comprising: mixing inorganiccompound particles with a gluing agent under stirring to form a gluingagent coat on surface of the inorganic compound particles; addingorganic pigments to the inorganic compound particles coated with thegluing agent, and mixing the resultant mixture under stirring to adherethe organic pigments on the gluing agent coat, thereby obtainingcomposite particles; and dissolving the inorganic compound particlesonly or both of the inorganic compound particles and the gluing agentfrom the composite particles. 4.-8. (canceled)
 9. A process forproducing a functional material comprising fine coloring particles,comprising: mixing inorganic compound particles with a gluing agentunder stirring to form a gluing agent coat on surface of the inorganiccompound particles; adding organic pigments to the inorganic compoundparticles coated with the gluing agent, and mixing the resultant mixtureunder stirring to adhere the organic pigments on the gluing agent coat,thereby obtaining composite particles; and dissolving the inorganiccompound particles only or both of the inorganic compound particles andthe gluing agent from the composite particles.